Discussion
Had a bit of an issue over the weekend with my E39 540i: it suddenly overheated, no warning whatsoever, just straight into the red. I pulled over and stopped, everything looked OK, water levels alright, so decided to carry on with the journey. Temp dropped back to normal after ABOUT 1/2 mile and as long as I kept it below 2k, it stayed fine.
After doing what I needed to do at the destination, I checked the water level again, and topped it up a bit, just to be on the safe side. Within 3 miles it was back into the red, so I stopped and checked the water level - only this time the water exploded out when I loosened the cap. So I let it cool for a bit, topped of the water (carefully) then drove it very slowly to the next gargage, about a mile further on. ALl this time the temp was in the red and I was getting check cooland temp and check coolant level warnings on the dash.
At the garage I made the decision to call the RAC, rather than try and drive the 120-odd miles home. I told them I thought the pump had failed. About an hour and a half later, the guy turned up, topped off the water, started the car, showed me where the air-bleed valve was (doh!) and then pronounced a failed pump. Recommended I change the pump then check to make sure I hadn't blown a head-gasket as well .....
That led to another hour wait and then a 3 hour journey home late on Sunday night- oh joy.
Ordered the parts Monday, and took the day off today to do the job - took about 2 hours to get the old pump off - and boy was it failed! The whole impeller had self-destructed into about 15 different bits. Just as I finished getting it all apart the new parts (water pump and thermostat - decided to change that justin) arrived, so on they went, together with 5 litres of fresh antifreeze, topped off with water. Got it all back together, checking for leaks once I'd filled up with coolant, got her started and everything looked fine - no leaks, came up to temperature nicely, the gauge sitting right in the middle of the gauge. Lovely! No head gasket failure - woo hoo!
Took her out for a quick drive, and decided to look at the temperature using the OBD function - it was up at 95C when I started driving and it just carried on climbing - 97, 99, 100, 102, 103, 105:
I was shatting meself - the head gaskets have gone. 
So I pulled over, stopped and checked everything again - no sign of leaks, but the pump outlet pipe was hard as a drum and the inlet pipe was stoney cold .... Drove back home, about 2 miles, and started stripping her down again, suspecting a failed thermostat - I was going to put the old one back on but when I got hold of the old one off the ruined water pump I noticed that it was stamped 105C.....
Off to the net to do some research
and found that this car runs at between 105 and 110C as normal. That was a bit of a shock, but I was certainly relieved. 
Back outside, put her back together again, and took her for a run - sure enough, temp settled at 107C, gauge right in the middle, no sign of leaks and this time the pump inlet hose was nice n toasty.
That was my day today, and I'm just glad the head-gaskets seem to be safe (for the moment).
After doing what I needed to do at the destination, I checked the water level again, and topped it up a bit, just to be on the safe side. Within 3 miles it was back into the red, so I stopped and checked the water level - only this time the water exploded out when I loosened the cap. So I let it cool for a bit, topped of the water (carefully) then drove it very slowly to the next gargage, about a mile further on. ALl this time the temp was in the red and I was getting check cooland temp and check coolant level warnings on the dash.
At the garage I made the decision to call the RAC, rather than try and drive the 120-odd miles home. I told them I thought the pump had failed. About an hour and a half later, the guy turned up, topped off the water, started the car, showed me where the air-bleed valve was (doh!) and then pronounced a failed pump. Recommended I change the pump then check to make sure I hadn't blown a head-gasket as well .....
That led to another hour wait and then a 3 hour journey home late on Sunday night- oh joy.
Ordered the parts Monday, and took the day off today to do the job - took about 2 hours to get the old pump off - and boy was it failed! The whole impeller had self-destructed into about 15 different bits. Just as I finished getting it all apart the new parts (water pump and thermostat - decided to change that justin) arrived, so on they went, together with 5 litres of fresh antifreeze, topped off with water. Got it all back together, checking for leaks once I'd filled up with coolant, got her started and everything looked fine - no leaks, came up to temperature nicely, the gauge sitting right in the middle of the gauge. Lovely! No head gasket failure - woo hoo!
Took her out for a quick drive, and decided to look at the temperature using the OBD function - it was up at 95C when I started driving and it just carried on climbing - 97, 99, 100, 102, 103, 105:
I was shatting meself - the head gaskets have gone. So I pulled over, stopped and checked everything again - no sign of leaks, but the pump outlet pipe was hard as a drum and the inlet pipe was stoney cold .... Drove back home, about 2 miles, and started stripping her down again, suspecting a failed thermostat - I was going to put the old one back on but when I got hold of the old one off the ruined water pump I noticed that it was stamped 105C.....
Off to the net to do some research
and found that this car runs at between 105 and 110C as normal. That was a bit of a shock, but I was certainly relieved. Back outside, put her back together again, and took her for a run - sure enough, temp settled at 107C, gauge right in the middle, no sign of leaks and this time the pump inlet hose was nice n toasty.
That was my day today, and I'm just glad the head-gaskets seem to be safe (for the moment).
107'c is about what I saw on my 540 too - so don't be alarmed.
Its an electric thermostat - by default it opens at the higher temperature, but it has the option of applying power to a little heater element around the wax on the thermostat to make it open sooner if conditions require it. (hot weather etc.)
Its an electric thermostat - by default it opens at the higher temperature, but it has the option of applying power to a little heater element around the wax on the thermostat to make it open sooner if conditions require it. (hot weather etc.)
glad its sorted. I had a simmilar worry at le amns 2 years back. The filler part cracked open, and I lost collant. Managed to get a new part shipped over and instaleld, and filled with normal water but didnt know how to bleed the system properly so the dial was right on the red, despite it not being a "hot" engine. Eventually, it settled down and we con tinued home but at every stop we had to replenish water- it seemed to take a huge amount, and had large air gaps. A;ll'd fine now, thankfully but I do think i should do the water pump soon
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